The present invention generally relates to processing of materials for growth of crystals. More particularly, the present invention provides an n-type gallium-containing nitride crystal synthesized by an ammonobasic or ammonoacidic technique. The present invention provides methods suitable for synthesis of crystalline nitride materials, as well as other crystals and materials. Such crystals and materials include, but are not limited to, GaN, AlN, InN, InGaN, AlGaN, and AlInGaN, and for manufacture of bulk substrates. Such bulk substrates can be used for a variety of applications including optoelectronic devices, lasers, light emitting diodes, solar cells, photoelectrochemical water splitting and hydrogen generation, photodetectors, integrated circuits, and transistors.
Gallium nitride containing crystalline materials serve as substrates for manufacture of conventional optoelectronic and electronic devices, such as blue light emitting diodes, lasers, power diodes, and transistors. Such optoelectronic and electronic devices have been commonly manufactured on sapphire, silicon, or silicon carbide substrates that differ in composition from the deposited nitride layers. In the conventional Metal-Organic Chemical Vapor Deposition (MOCVD) method, deposition of GaN is performed from ammonia and organometallic compounds in the gas phase. Although successful, conventional growth rates achieved make it difficult to provide a bulk layer of GaN material. Additionally, dislocation densities are also high and lead to poorer optoelectronic device performance.
For many applications an n-type GaN substrate is desirable, having excellent crystalline and electrical properties and low cost. Quasi-bulk GaN substrates grown by hydride vapor phase epitaxy (HVPE) often do quite well in this regard but a number of improvements are desirable, as described below.
What is needed is a method for low-cost manufacturing of n-type nitride materials that have excellent crystallographic and electrical properties. The present invention fulfils this need among others.